The present invention relates to a fuel-storing device in an engine-powered transporter. The invention is intended to be used for storing gaseous fuels for transport means, expediently in the form of motor vehicles such as, for example, passenger cars.
In connection with engine-powered transport means, for example cars, airplanes and rockets, there is a general requirement for safe, effective and economical storage of engine fuel.
As far as combustion-engine-powered vehicles are concerned, for example in the form of passenger cars, it has in recent years become increasingly desirable to use engines which are powered with alternative types of fuel compared with those used in currently conventional petrol- and diesel-powered engines. As examples, engines can be cited which are powered by natural gas, alcohol-based fuels (methanol or ethanol) and/or hydrogen gas. The reasons for the adoption of new fuels are at least partly based on the fact that the earth""s reserves of fossil fuels are thought to be limited and also because of growing public opinion and increasingly stringent legislation that favors environmentally friendly engine fuels and vehicles.
In this context, it has been established that hydrogen gas can be used as fuel for engine-powered vehicles and that an engine system of this kind then represents a suitable alternative to conventional petrol-powered or diesel-powered combustion engines. The reason why hydrogen gas is attractive as such an alternative fuel includes that it can be produced using, for example, solar energy. Moreover, hydrogen gas burns without carbon dioxide (CO2) being generated, a further advantage, since generation of carbon dioxide, for example through burning of fossil fuels, is thought to contribute to the so-called greenhouse effect.
Where hydrogen is used as fuel in connection with motor vehicles, however, there are certain problems. Included among these problems is the difficulty associated with achieving a storage system on board a vehicle which works in practice. According to known systems, various types of hydrogen containers are used in vehicles which store the hydrogen either in gaseous form, in liquid form, bound in metal hydrides or absorbed in carbon.
Where hydrogen is stored in gaseous form, a very high storage pressure is required; more precisely, pressures of the order of magnitude of 300 bar. This causes a relatively high weight and cubic capacity being required for such storage tanks. Moreover, such a system can constitute a safety risk in connection with, for example, passenger cars.
When hydrogen is stored in liquid form, a very low temperature is required for maintained storage. This calls for costly cooling systems, which is a disadvantage. An advantage of storing hydrogen in liquid form is, however, that the vehicle in question acquires a relatively long range of travel.
When hydrogen is stored in a metal hydride system; that is, in one in which the hydrogen molecules are bound in a metal hydride structure and are released upon heating, a storage system is also required which is relatively heavy. In addition, devices are required for heating the metal hydride structure to enable the hydrogen""s liberation.
When hydrogen absorbed in carbon is stored, a very low storage temperature is required for the hydrogen to enable it to be bound to the carbon. According to what has been stated above, this is a disadvantage.
It can further be established that previously known systems which are based on hydrogen-powered fuel cells lead to difficulties in connection with tubings; that is, connections to, and distribution within the fuel cells. These difficulties are hard to solve regarding leakage, flow, collision and safety aspects. Moreover, previously known hydrogen gas containers have been space-consuming, expensive, temperature-sensitive, heavy and/or difficult to place in the transporting vehicle.
In U.S. Pat. No. 5,653,961, a system is described for storing hydrogen gas in so-called nanostructures; that is, microstructures which are constructed as a matrix of graphite laminae having dimensions which are tailored to the acceptance of hydrogen molecules. Nanostructures of this kind can be used to store a large quantity of hydrogen gas per unit of volume compared with previously known storage systems. This means that a fuel-cell-powered vehicle having a hydrogen gas tank which has a cubic capacity of, for example, 40 liters and comprises nanostructures, can acquire a travel range of just over 12,800 km.
By virtue of German Document DE 19708404, a vehicle chassis having a special fuel-storage space accommodated in the lower section of the chassis is known. More precisely, this fuel storage space is constituted by a defined space adjoining the floor of the vehicle. In the fuel-storage space, a number of different types of energy carriers can be arranged and used; the energy carriers being installed in this case from the side of the vehicle. In this document, a hydrogen gas container is cited as a conceivable energy-storage method. The arrangement is set up as an exchangeable system; i.e., a fuel-storage system which is configured such that its various fuel containers can easily be reached and individually exchanged, instead of being filled at regular intervals.
In the light of the above, it can be seen that there is a need for storage systems for hydrogen which are cost-effective, economical, safe, lightweight, easy to handle and more compact then previously known storage systems.
The present invention in its several disclosed embodiments alleviates the drawbacks described above with respect to conventionally designed devices for storing engine fuel and incorporates several additional beneficial features.
An object of the present invention is to provide a device for storing engine fuel, more particularly hydrogen, in vehicles in which the above-mentioned problems may effectively be solved. This is achieved by means of a device, the distinguishing features of which are described in greater detail hereinbelow.
The invention constitutes a device for storing fuel in an engine-powered transport vehicle or means having at least one closed construction element which is incorporated as an integral part of the body or chassis structure of the transport means. The invention is characterized in that the closed construction element, moreover, is arranged as a storage unit for the fuel.
As a result of the invention, a number of advantages are attained. First and foremost, it can be noted that the invention facilitates safe and effective storage of hydrogen gas in a transport means. According to a preferred embodiment, existing structures in the transport means are configured with a nanostructure, for example nanofibers of carbon, which facilitates storing hydrogen gas with a high-pack efficiency. This allows, in turn, a high range of travel for the transport means.
Preferably, use is made of a nanostructure that is integrated within a chassis structure belonging to the transport means or within some other exterior or interior construction element, for example panels, doors, hatches or a floor structure of the transport means.
The invention further allows hydrogen gas to be stored more safely and economically than is the case with known systems. The fact that the invention utilizes existing structures in a transport means or vehicle signifies that weight increases are minimized which would otherwise follow if a separate tank were used for the fuel.
According to a preferred embodiment, a barrier layer of metal hydride is used in the above-mentioned construction element. In this way, a totally leak-proof storage of the fuel in question is provided.
The beneficial effects described above apply generally to the exemplary devices, mechanisms and methods disclosed herein for the storage of fuel in a carrying vehicle. The specific structures and steps through which these benefits are delivered will be described in greater detail hereinbelow.